Pro-Russian activists clash with police at the regional administration building in Donetsk, Ukraine, Sunday, April 6, 2014. In Donetsk a large group of people surged into the provincial government building and smashed windows. A gathering of several hundred, many of them waving Russian flags, then listened to speeches delivered from a balcony emblazoned with a banner reading ìDonetsk Republic.î (AP Photo/Alexander Ermochenko) ( Ukraine )

Pro-Russian supporters clash with members of the riot police as they storm the regional administration building in the eastern Ukrainian city of Donetsk on April 6, 2014. About 50 protesters chanting "Donetsk is a Russian city!" broke through police lineson April 6 and stormed inside the main administration building of the eastern Ukrainian city. The activists moved away from a crowd of about 2,000 rallying on the main city square and threw firecrackers at police surrounding the government seat before raising the Russian flag above the 11-storey building. AFP PHOTO/ ALEXANDER KHUDOTEPLY ( 528714142 )

Pro-Russian supporters clash with members of the riot police as they storm the regional administration building in the eastern Ukrainian city of Donetsk on April 6, 2014. About 50 protesters chanting "Donetsk is a Russian city!" broke through police lineson April 6 and stormed inside the main administration building of the eastern Ukrainian city. The activists moved away from a crowd of about 2,000 rallying on the main city square and threw firecrackers at police surrounding the government seat before raising the Russian flag above the 11-storey building. AFP PHOTO/ ALEXANDER KHUDOTEPLY ( 528714068 )

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Pro-Russian supporters clash with members of the riot police as they storm the regional administration building in the eastern Ukrainian city of Donetsk on April 6, 2014. About 50 protesters chanting "Donetsk is a Russian city!" broke through police lineson April 6 and stormed inside the main administration building of the eastern Ukrainian city. The activists moved away from a crowd of about 2,000 rallying on the main city square and threw firecrackers at police surrounding the government seat before raising the Russian flag above the 11-storey building. AFP PHOTO/ ALEXANDER KHUDOTEPLY ( 528716461 )

Pro-Russian supporters clash with members of the riot police as they storm the regional administration building in the eastern Ukrainian city of Donetsk on April 6, 2014. About 50 protesters chanting "Donetsk is a Russian city!" broke through police lineson April 6 and stormed inside the main administration building of the eastern Ukrainian city. The activists moved away from a crowd of about 2,000 rallying on the main city square and threw firecrackers at police surrounding the government seat before raising the Russian flag above the 11-storey building. AFP PHOTO/ ALEXANDER KHUDOTEPLY ( 528714095 )

Pro-Russian activists clash with police at the regional administration building in Donetsk, Ukraine, Sunday, April 6, 2014. In Donetsk a large group of people surged into the provincial government building and smashed windows. A gathering of several hundred, many of them waving Russian flags, then listened to speeches delivered from a balcony emblazoned with a banner reading ìDonetsk Republic.î (AP Photo/Andrey Basevich) ( APTOPIX Ukraine )

Pro-Russian protesters hold Russian national flags during the rally in eastern Ukrainian city of Donetsk on April 6, 2014. "Europe must not relax" and needs to stand firm on the Ukraine crisis until Russia "shows it is serious" by clearly pulling back its troops from the border, Europe's foreign ministers said on April 4, 2014 in Brussels on the steps of a Euro-African summit.
AFP PHOTO/ ALEXANDER KHUDOTEPLY ( 528712189 )

Pro-Russian masked activist waves a Russian national flag in front of the regional administration building in Donetsk, Ukraine, Sunday, April 6, 2014. In Donetsk a large group of people surged into the provincial government building and smashed windows. A gathering of several hundred, many of them waving Russian flags, then listened to speeches delivered from a balcony emblazoned with a banner reading a "Donetsk Republic". (AP Photo/Andrey Basevich) ( Ukraine )

Pro-Russian supporters wave a Russian flag as they storm the regional administration building in the eastern Ukrainian city of Donetsk on April 6, 2014. About 50 protesters chanting "Donetsk is a Russian city!" broke through police lineson April 6 and stormed inside the main administration building of the eastern Ukrainian city. The activists moved away from a crowd of about 2,000 rallying on the main city square and threw firecrackers at police surrounding the government seat before raising the Russian flag above the 11-storey building. AFP PHOTO/ ALEXANDER KHUDOTEPLY ( 528714231 )

A wounded policeman receives medical assistance following clashes with pro-Russian activists who stormed the Regional Security Service of Ukraine in eastern Ukrainian city of Lugansk on April 6, 2014. AFP PHOTO/ IGOR GOLOVNIOVI ( 528715191 )

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Pro-Russian activists evacuate a wounded following clashes with anti-riot forces after storming the Regional Security Service of Ukraine in eastern Ukrainian city of Lugansk on April 6, 2014. AFP PHOTO/ IGOR GOLOVNI ( 528716473 )

In this photo taken on Saturday, April 5, 2014, Oleh Lyashko, center left, leader of Ukrainian Radical Party and presidential candidate who supported the protests that ousted Russian-leaning president Viktor Yanukovych, poses with Ukrainian soldiers and officers at their camp near Ukraine-Russian border outside Chernihiv, 140km (87 miles) northeast of Kiev, Ukraine. Ukraine's security service said Saturday it has detained a 15-strong armed gang planning to seize power in an eastern province on the border with Russia. (AP Photo/Osman Karimov) ( Ukraine )